Prefabricated fireplace using prefabricated metal firebox



Jan. 11, 1966 J. E. MILAN 3,228,387

PREFABRICATED FIREPLACE USING PREFABRICATED METAL FIREBOX Filed April 12, 1962 3 Sheets-Sheet 1 F I G.

INVENTOR. JOSEPH E. MILAN BY wg w M Attorneys J. E. MILAN 3,228,387

PREFABRICATED FIREPLACE USING PREFABRICATED METAL FIREBOX Jan. 11, 1966 3 Sheets-Sheet 2 Filed April 12, 1962 FIG. 3

FIG. 2

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1 II I ll il ll IUHI I! ll ll INVENTOR JOSEPH E. MILAN Attorneys J. E. MILAN 3,228,387

PREFABRICATED FIREPLACE USING PREFABRICATED METAL FIREBOX Jan. 11, 1966 5 Sheets-Sheet 5 Filed April 12, 1962 FIG. 8

FIG. 9

INVENTOR. JOSEPH E. MILAN Attorneys United States Patent 3,228,387 PREFABRICATED FIREPLACE USKNG PRE- FABRICATEI) METAL FIREBGX Joseph E. Milan, 2975 S. Hudson St, Denver 22, Colo. Filed Apr. 12, 1962, Ser. No- 186,929 1 Claim. (Cl. 126-138) This invention relates to building construction and more particularly to lightweight, preformed, fireplace forms for residential fireplace installations.

Contemporary fireplace construction for private residences is normally either of solid masonry construction or a masonry facing over a prefabricated steel unit which serves as and includes the smoke dome, down-draft shelf, damper, throat and firebox. An example of the latter are the prefabricated steel units sold by the Vega Industries, Inc. under the trademark Heatilator, and the instant invention has particular utility therewith as explained in more detail below.

Today, the high cost and high risk method of building a solid masonry fireplace brick by brick is very time consuming and, not only is the cost of materials and labor for construction high, but there is the added necessity of reinforcing the supports for the fireplace. Particularly in existing structures fioor joists and the supporting surface on which the fireplace and hearth are to be placed must be substantially reinforced. While the installations which include the masonry facing over a prefabricated steel unit use relatively few fire brick, there is still the necessity of reinforcing existing floor joists and supporting surfaces, upon which the installation is to be placed so as to accommodate the weight of the insulating brick and chimney. In the past, conventional installation of steel fireplaces required a concrete block base with a firebrick hearth on top to support the steel unit. Additionally, the fireplace form itself had to be surrounded by an insulating brick or block enclosure and other extensive insulation in order to prevent charring and burning of the adjacent wooden portions of residential construction. In fact, most building codes are rather demanding as to the insulation qualities, spacing and amount of insulation which must be included with the prefabricated steel units. Also, with both the solid masonry construction and the prefabricated steel unit a location of choice is usually an outside wall, although if desired the fireplace may be placed centrally of a room or adjacent an interior wall. With the latter construction, a stanchion or additional brace is necessary between the basement floor and the joists supporting the floor upon which the fireplace is to be installed.

Accordingly, it is an object of this invention t provide lightweight, inexpensive and easily installed fireplace forms for residential fireplace installations which are particularly adapted for use with prefabricated steel, unit-type fireplace installations, and which do not require special reinforcing of fioor joists and the like upon which the fireplace is to be installed.

It is another object of this invention to provide an inexpensive, lightweight, preformed fireplace installation requiring a minimum of space for installation, and, also, provide adequate insulation for complying with conventional building codes.

It is another object of this invention to provide lightweight precut fireplace forms which may be rapidly installed with a minimum of instruction.

Briefly, in one embodiment, a fireplace installation according to the instant invention includes a prefabricated steel unit and a novel enclosure therefor which includes a masonry-style fireplace facing which is very lightweight and may be quickly installed without special reinforcing or bracing of the supporting structures. The form itself consists of top, bottom and side members fabricated of a special lightweight perlite concrete. All of the form members are specially constructed for rapid interlocking without cutting or special installation tools. The perlite concrete may be easily sawed, nailed and otherwise fastened as desired.

Utilizing the above noted perlite and cement mix it is possible to use a thin brick or stone facing thereby greatly reducing the overall weight of the finished brick or stone faced fireplace.

Other objects and further features and advantages of fireplace construction according to the concepts of this invention will become obvious to those skilled in the art from a study of the following detailed drawing description. these drawings:

FIG. 1 is an isometric view, partially broken away, of one form of fireplace construction according to the concepts of this invention;

FIG. 2 is a side elevation of a completed fireplace;

FIG. 3 is a sectional view of the installation of FIG. 2 illustrating the positioning of a metal fireplace therein;

FIG. 4 is a top sectional View of a portion of the instal lation of FIG. 2;

FIG. 5 is a top elevation of the hearth and base of the installation of FIG. 2;

FIG, 6 is a front elevation, in partial section, of a modified hearth according to the invention;

FIG. 7 is a side elevation of a side member of the fireplace construction of the invention;

FIG. -8 is a front plan view of a front panel of the installation of FIG. 1;

FIG. 9 is a top elevation of one form of a method of fabrication of a unit for assembly with a structure such as shown in FIGS. 1 through 8; and

FIG. 10 is a fragmentary sectional view through the front upright facing of the fireplace construction of FIG. 1 as cast in the form of FIG. 9.

The basic enclosure of the fireplace installation of FIG. 1 is comprised of a plurality of preformed and interlocking panel sections all of which are fabricated of a lightweight material having a very low ,a factor or coefficient of thermal conductivity. In a preferred embodiment, the panels are formed of a hardened mixture of the following materials in the indicated quantities:

(l) 94 lbs. of Portland cement.

(2) 1-10 cubic ft. of perlite (exfoliated volcanic glass).

(3) An air entraining agent capable of entraining about 6-45 cubic ft. of air in the mixture such as neutralized Vinsol resin (Vinsol is the trademark of Hercules Powder C0. and a thermoplastic resin, acid number 94, specific gravity 1.218, and having a softening point in the range of 116 0.), in the amount of 1 oz. per cubic ft. of perlite; /2 lb. sodium lignum sulfonate; or 1 oz. per cubic ft. of sulfonated hydrocarbons.

(4) An accelerating agent capable of hardening the mix is preferred, and economically to harden it in about 24 hours, such agents as varying grades of calcium chloride, preferably a commercial grade calcium chloride. In very severe weather about 2 lbs. of the calcium chloride per 94 lb. sack of Portland cement and in dry warm weather from A2 to lb. is used.

(5) Suificient water to mix and varying from 6 to 16 gals.

While in the foregoing discussion 1 oz. of the Vinsol resin was indicated, from /4 to 2 ozs. may be used depending upon the weather conditions. The same is true of the sulfonated hydrocarbons in the range of from A to 2 ozs. per cubic ft. of perlite.

Other cementitious materials may be used besides the Portland cement; for example, a commercial grade of gypsum. In such a mix approximately lbs. of gypsum are mixed per 1-10 cubic tit. of perlite and an air entraining agent, preferably calcium lignum sulfonate, is mixed therewith. In this mix no accelerator is nec essary.

Another possible mix is 1 cubic ft. of perlite per 1- 100% by weight of sodium silicate (water glass) with carbon dioxide or heat to harden.

Other cementitious binder materials for the perlite might be used, and the desired end result is a density of the finished product of about 30 lbs. per cubic ft. and preferably within the range of 15-65 lbs. per cubic ft. in order to keep the finished enclosure installation of light weight and easy manipulability. Other light weight material as aggregate may be used in place of perlite, such as exfoliated vermiculite, mica, pumice, etc.

Referring to FIG. 1, a fireplace installation according to the concepts of this invention is shown to be an enclosure for a prefabricated steel unit (see FIG. 3) of the type above discussed and includes a pair of side members or walls 15 and 16, a back member or wall 17, a top or roof 18, a bottom or base section 19, anda front panel 30. The roof 18 has a circumferential opening formed therethrough of sufficient dimension as to accommodate and frictionally engage the chimney or fireplace flue. At least a portion of the peripheral edges of the various members just discussed are rabbeted or stepped in order to interlock for rapid assembly and seal the enclosure. For example, the stepped edge 18A of the roof 18 and the stepped edge 16A of the side 16 are of complementary shaping for rapid, flush andcontiguous interlocking and provide a tortuous flow path to prevent flow of gases therethrough.

The hearth, in one form, is T-shaped and comprised of the leg section 19 and the forward or head portion 20 which is covered with thin slabs 21 of brick or stone. The upright'front face section 22 of the installation is, as are all the other portions of the enclosure, fabricated of the same lightweight perlite-cement mix above discussed, .and is covered with thin slabs 23 of brick or stone facing. A more detailed discussion of the construction of the front face 22 and exposed head 20 will be set forth hereafter with reference to FIGS. 6, 8 and 10.

As noted above, the various members which make up the rear enclosure for the prefabricated unit are stepped or keyed for rapid interlocking. In FIG. such a step 19A extends around three sides of the hearth leg section 19 and stops short of the oppositely extending arms 20A and 20B of the head section 20. The arms 20A and 20B are of suflicient dimension as to receive the front facing 22 thereon. Each of the sides and 16, side 15 being shown in FIG. 7, includes a stepped portion 15A along the rear and across the top edges, and down the front edge a sufficient distance as to present flat edges 15Bthe vertical extent of the rear of front face 22 when the installation is assembled.

The rabbeted portion 15A on the forward edge of the sides is arranged for mating with the rabbeted edges 30A, FIG. 8, of the front panel 30. Stepped portions of the front panel 30 extend across the top and down both side edges but not across the bottom. The bottom includes an outwardly extend-ing foot 30B which is arranged to seat behind the front facing 22 when the enclosure is assembled.

A finished residential fireplace installation is shown in FIG. 2 in which a mantle 50 has been placed on the top of the facing 22 and a pair of wooden end panels 31 have been mounted along opposed sides of the facing. A wooden front panel 32 (as best seen in FIG. 3) is thereafter placed above the mantle, across the sides 31, and extends upwardly to the ceiling 33. Preferably quarter round molding 32A is added to lend a finished appearance. The panels 31 and 32 are easily installed and interconnected as by mounting fur stripping pieces 34 about the inner face of the front and side panels, the ceiling, and along the wall 35 against which the fire place is positioned A Heatilatorunit 36 is-shownin FIG. 3 in dashed lines as it might appear in a finished installation. The foregoing arrangement lends itself ideally to various interior decorating schemes, limited only by the imagination of the designer. The paneling such as the wooden panels 31 and 32 may be of any material, color or design as desired without extensive cost. Likewise, the mantle 50 may be of almost any size or shape, again with little increase in cost of installation.

The Heatilator unit 36 (FIG. 3) includes a firebox 60, throat 60a, and smoke dome 62. A damper 70 is provided for the throat of the firebox. In the upper portion of the smoke dome, although not indicated in the drawing, a conventional downdraft shelf adjacent the damper 70 is included. The opening through the front face 22 is slightly smaller than the opening through the front face of firebox 60 so it may abut against the inner wall of the front facing.

While brick slabs have been illustrated for the front facing 22 and the forward portion 20 of the hearth, it should be understood that thin slabs of stone or artificial masonry material can be used to complement the decorating scheme being planned.

The wall members and the roof making up the Heatilator enclosure itself, are fabricated of the cement-perlite material, above discussed, and are on the order of two inches in thickness. The sectional view of FIG. 3 indicates the base to be on the order of twice as thick, or four inches, but, because of the extremely light weight of the material being used, this does not result in a member which is difficult to handle.

The hearth sections 19 and 20 are cast as a single unit, FIG. 5, and in the casting operation the brick or rock facing 21 is firmly secured thereto. A mold of the type shown in FIG. 9 is assembled and the brick or tile facing material 21 is positioned on the bottom thereof. Grouting material 43 is then forced into the cracks between the positioned brick or tile. A quantity of the perlite-cement mix, in fluid form, is poured on top of the brick or tile, tamped and smoothed and then permitted to harden.

A more detailed understanding of the fabrication of the brick or slab faced portions will be had from a study of FIGS. 9 and 10. In FIG. 9 a generally rectangular wooden knockdown form 40 is shown having four subsantially identical side walls 41 mounted on a wooden bottom 42. Three smaller wall members 44 are to define the opening through the front facing which is to be cast. A plurality of brick slabs 45 are positioned on mold bottom 42 and grouting material 43 placed therebetwe'en. In FIG. 10 a preferred manner of placement and grouting between the slabs 45 is shown in greater detail. In order to give a pointed and realistic appearance to the brick slabs 45, thin flexible sponge rubber spacers 46 are positioned between the slabs on mold bottom 42. The grouting 43 is poured over the back of the slabs and trowelled to fill the spaces between the slabs. The desired quantity of cementaperlite mix 47 is added and allowed to harden. Because of the knockdown character of the mold, after the hardening period, the sides for the mold are easily disassembled and the finished facing slab is lifted to an upright position. Thereafter, the rubber spacers 46 are removed thereby resulting in a realistic pointed appearance for the facing. In FIG. 10 the thickness of the slabs 45 has been exaggerated somewhat for purposes of explanation. In actual practice they are on the order of one-half inch thick.

In actual tests of the material of which the enclosure according to this invention is fabricated, a coeflicient of thermal conductivity or a factor for a two-inch thickness was found to be on the order of 0.0185 and for a four-inch thickness on the order of 0.0125. In one test, a flame was placed closely adjacent one side of a 1% inch slab and the temperature was measured on the other side directly opposite the flame. Upon initiation of the test the temperaturewas 70 F.--After forty minutes the temperature had risen to 130 F. without burning or spalling of the material. A 3% inch slab was subjected to similar tests and the initial starting temperature of 70 F. increased to only 80 F. after the forty minute test. Again, in the test of the 3% inch thickness slab no charring, burning or spalling of the material occurred. The weight or density of the material tested was 27 pounds per cubic foot.

In some instances a raised hearth is desirable, a construction as shown in FIG. 6 is used since it is light weight and strong enough to support the fireplace structure. A base is made of interlocked slabs (using the stepped interlock described above) placed on edge. Front and back slabs 68 (only the front slab shows in the drawing) are in one size, 4" x 8" x 5'5 standing edgewise on a base. These front and rear slabs are grooved to receive end slabs 61. The front and back slabs are identical as are the end slabs for convenience of manufacture. The end slabs are about 3" x 8" X 4'4" and are placed edge- Wise in interlocking position with the front and back slabs. Intermediate slabs 69 are placed endwise in interlocking position with grooves 63 in the front and rear slabs. The intermediate slabs are 3" X 8" x 38".

The front and end slabs are covered with facing members 21, either brick or stone, as explained above. The members of the base are assembled on location and where necessary may be secured together in any convenient manner. A top cover 65, which is made of a slab of the perlite-cernent mix, is placed over the assembled base. The top slab is covered with facing 21 as desired. The facing members are grouted to provide a neat, natural appearing structure. The edge of the top slab is covered with small facing members 66 to complete the hearth. The metal fireplace insert is set on fire brick, as explained above, and the enclosure completed.

Having described my invention in detail with sufiicient particularity as to enable those skilled in the art to practice it, what I desire to have protected by Letters Patent is set forth in the following claim.

I claim:

The combination of a perfabricated metal firebox unit and a prefabricated enclosure comprising a base section having an integral leg section and a forward portion, a relatively thin outer masonry facing bonded around the exposed 'edges of the base section and across a major portion of the forward portion of its upper surface, an upright fireplace front face section having a fireplace opening formed therethrough, the front face section being seated on the base section along and adjacent the rear extent of the masonry facing on the forward portion, a "relatively thin outer masonry facing bonded about the exposed edges and face of the front face section, a pair of subsantially identical opposed side walls, a back wall and an apertured roof, the side and back walls and the roof having abutting edges keyed for flush and contiguous interlocking, the respective bottom edges of the side and back walls being keyed to contiguously and flushly interterlock with complementary keying structure on the leg of the base section, all the complementary keyed edges being so constructed as to provide a tortuous engaging surface to prevent passage of gases therethrough, a front panel, the top and side edges thereof being keyed for complementary interlocking with the roof and upper portions of the side walls and having its lower edge seated on the upper edge of the fireplace front face section, the base and front face sections, the side and rear walls, the apertured roof, and the front panel all being fabricated of relatively thin slabs of hardened light Weight, cementitious material having a low coeflicient of thermal conductivity, the metal firebox unit being supported on the base against the back side of the front face section and including metal wall means forming a firebox with an open front of substantially the same dimension as the opening through said front face section, a throat opening from the top of the firebox and having a damper therein, and a smoke dome therefor, a chimney flue opening from the smoke dome, the outer dimension of the chimney time being slightly smaller than the aperture through the roof and being frictionally engaged thereby, and the resulting structure providing a fireplace installation.

References Cited by the Examiner UNITED STATES PATENTS 1,082,231 12/ 1913 Nale 126--138 1,342,329 6/1920 Freeman 126l20 2,162,658 6/1939 Wieslander -533 2,429,748 10/ 1947 Dollinger l26121 2,808,824 10/1957 Cage 126120 2,821,975 2/1958 Thulman 12612O 2,875,747 3/1959 Fish 126-427 3,035,375 5/1962 Williams 50533 FOREIGN PATENTS 589,638 6/1947 Great Britain. 611,806 11/1948 Great Britain.

FREDERICK L. MATTESON, JR., Primary Examiner.

JAMES W. WESTHAVER, Examiner. 

